It's always emphasized in literature that endothermy enables high growth rates but requires more food.
But look at frogs, for example: bullfrogs, toads, pacman frogs etc. They would readily eat a quarter their weight a day, and they grow real fast (I used to keep pet frogs: pacmans, for example, become more that twice as big in one season). And all of that despite being ectotherms. How is that possible?